Wash and peel sweet potatoes. Cut off woody portions and ends, cut into quarters. Cook in salted boiling water for 25 to 30 minutes or until fork tender. Drain.

Preheat oven to 350 degrees. Transfer potatoes into large mixing bowl. Mash lightly. Stir in sugar, 1/4 cup melted butter, milk, eggs, and vanilla. Transfer mixture into a 2 quart casserole dish.

In small mixing bowl, combine brown sugar, oats or pecans, flour and 2 Tbsp melted butter. Sprinkle over casserole.

Bake, uncovered, for 30-35 until bubbly hot.